mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-25 11:37:56 +00:00
147 lines
3.0 KiB
C
147 lines
3.0 KiB
C
/*
|
|
* CACHE.C
|
|
*
|
|
* Block cache for dump
|
|
*
|
|
* $FreeBSD$
|
|
*/
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/stat.h>
|
|
#include <sys/mman.h>
|
|
|
|
#ifdef sunos
|
|
#include <sys/vnode.h>
|
|
|
|
#include <ufs/fs.h>
|
|
#include <ufs/fsdir.h>
|
|
#include <ufs/inode.h>
|
|
#else
|
|
#include <ufs/ufs/dir.h>
|
|
#include <ufs/ufs/dinode.h>
|
|
#include <ufs/ffs/fs.h>
|
|
#endif
|
|
|
|
#include <protocols/dumprestore.h>
|
|
|
|
#include <ctype.h>
|
|
#include <stdio.h>
|
|
#ifdef __STDC__
|
|
#include <errno.h>
|
|
#include <string.h>
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
#endif
|
|
#include "dump.h"
|
|
|
|
typedef struct Block {
|
|
struct Block *b_HNext; /* must be first field */
|
|
off_t b_Offset;
|
|
char *b_Data;
|
|
} Block;
|
|
|
|
#define HFACTOR 4
|
|
#define BLKFACTOR 4
|
|
|
|
static char *DataBase;
|
|
static Block **BlockHash;
|
|
static int BlockSize;
|
|
static int HSize;
|
|
static int NBlocks;
|
|
|
|
static void
|
|
cinit(void)
|
|
{
|
|
int i;
|
|
int hi;
|
|
Block *base;
|
|
|
|
if ((BlockSize = sblock->fs_bsize * BLKFACTOR) > MAXBSIZE)
|
|
BlockSize = MAXBSIZE;
|
|
NBlocks = cachesize / BlockSize;
|
|
HSize = NBlocks / HFACTOR;
|
|
|
|
msg("Cache %d MB, blocksize = %d\n",
|
|
NBlocks * BlockSize / (1024 * 1024), BlockSize);
|
|
|
|
base = calloc(sizeof(Block), NBlocks);
|
|
BlockHash = calloc(sizeof(Block *), HSize);
|
|
DataBase = mmap(NULL, NBlocks * BlockSize,
|
|
PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
|
|
for (i = 0; i < NBlocks; ++i) {
|
|
base[i].b_Data = DataBase + i * BlockSize;
|
|
base[i].b_Offset = (off_t)-1;
|
|
hi = i / HFACTOR;
|
|
base[i].b_HNext = BlockHash[hi];
|
|
BlockHash[hi] = &base[i];
|
|
}
|
|
}
|
|
|
|
ssize_t
|
|
cread(int fd, void *buf, size_t nbytes, off_t offset)
|
|
{
|
|
Block *blk;
|
|
Block **pblk;
|
|
Block **ppblk;
|
|
int hi;
|
|
int n;
|
|
off_t mask;
|
|
|
|
/*
|
|
* If the cache is disabled, or we do not yet know the filesystem
|
|
* block size, then revert to pread. Otherwise initialize the
|
|
* cache as necessary and continue.
|
|
*/
|
|
if (cachesize <= 0 || sblock->fs_bsize == 0)
|
|
return(pread(fd, buf, nbytes, offset));
|
|
if (DataBase == NULL)
|
|
cinit();
|
|
|
|
/*
|
|
* If the request crosses a cache block boundary, or the
|
|
* request is larger or equal to the cache block size,
|
|
* revert to pread(). Full-block-reads are typically
|
|
* one-time calls and caching would be detrimental.
|
|
*/
|
|
mask = ~(off_t)(BlockSize - 1);
|
|
if (nbytes >= BlockSize ||
|
|
((offset ^ (offset + nbytes - 1)) & mask) != 0) {
|
|
return(pread(fd, buf, nbytes, offset));
|
|
}
|
|
|
|
/*
|
|
* Obtain and access the cache block. Cache a successful
|
|
* result. If an error occurs, revert to pread() (this might
|
|
* occur near the end of the media).
|
|
*/
|
|
hi = (offset / BlockSize) % HSize;
|
|
pblk = &BlockHash[hi];
|
|
ppblk = NULL;
|
|
while ((blk = *pblk) != NULL) {
|
|
if (((blk->b_Offset ^ offset) & mask) == 0)
|
|
break;
|
|
ppblk = pblk;
|
|
pblk = &blk->b_HNext;
|
|
}
|
|
if (blk == NULL) {
|
|
blk = *ppblk;
|
|
pblk = ppblk;
|
|
blk->b_Offset = offset & mask;
|
|
n = pread(fd, blk->b_Data, BlockSize, blk->b_Offset);
|
|
if (n != BlockSize) {
|
|
blk->b_Offset = (off_t)-1;
|
|
blk = NULL;
|
|
}
|
|
}
|
|
if (blk) {
|
|
bcopy(blk->b_Data + (offset - blk->b_Offset), buf, nbytes);
|
|
*pblk = blk->b_HNext;
|
|
blk->b_HNext = BlockHash[hi];
|
|
BlockHash[hi] = blk;
|
|
return(nbytes);
|
|
} else {
|
|
return(pread(fd, buf, nbytes, offset));
|
|
}
|
|
}
|
|
|